Ultrasound Scans

Original Editor - Rachael Lowe Top Contributors - Mark Smith, Aaron Bergeron, Hayden Rose, Lucinda hampton, Kim Jackson, Admin, Rachael Lowe, Claire Knott, Cindy John-Chu and Tony Varela

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Ultrasound: An Overview

Not to be confused with Therapeutic Ultrasound, medical ultrasonography uses high frequency broadband sound waves in the megahertz range that are reflected by tissue to varying degrees to produce (up to 3D) images (commonly associated with imaging the fetus in pregnant women). Ultrasonography is generally considered safe imaging with the World Health Organizations saying:

"Diagnostic ultrasound is recognized as a safe, effective, and highly flexible imaging modality capable of providing clinically relevant information about most parts of the body in a rapid and cost-effective fashion".

There are several divisions in which ultrasound can be used as a diagnostic tool. These divisions include cardiovascular ultrasound, abdominal ultrasound, and musculoskeletal ultrasound.

• Cardiovascular Ultrasound - The use of diagnostic ultrasound to view the musculature of the heart as well as arteries and veins throughout the human body.
• Abdominal Ultrasound - The use of diagnostic ultrasound to view the abdominal viscera and the contents within them. This also includes the viewing of fetus in utero.

Musculoskeletal Ultrasound

Musculoskeletal Ultrasound can be defined as the use of diagnostic ultrasound with the intent to view structures of the musculoskeletal system. These structures include muscles, tendons, ligaments, nerves, and joints. The use of ultrasound to view these structures can be helpful in the diagnosis of musculoskeletal pathologies including, but not limited to, tendinopathies, strains, sprains, tears, and arthritic changes within joint spaces.

Equipment Involved In MSK Ultrasound

• Ultrasound Tower
  • Tower styles will vary depending upon different manufacturers.

• Transducer
  • Phased - use of low frequency to visualize deeper structures such as the heart. The smaller allows for navigation around the ribs to view contents within the ribcage.
  • Linear - use of high frequency and high resolution up to 5cm, generally used for MSK ultrasound.
  • Curved - use of lower frequency used to visualize deeper structures such as abdominal organs, viscera, obstetrics, and gynecological needs.

Transducer types

• Ultrasound Medium
  • A specific gel manufactured for ultrasound transmission will be needed to use in adjunct with the transducer heads.

This short video gives a animated insight into how US scans work

How to Perform an MSK Ultrasound Scan

The overall process to performing an ultrasound is relatively simple. This is one advantage to using ultrasound for diagnostic imaging. Once you have gathered all necessary equipment, you will want to position the patient in a manner that allows access to the desired area for scanning while maintaining patient comfort. You will then apply a gel medium to the area of choice and place the transducer onto the gel. These steps take place before powering on the machine to prevent from overheating the transducer head. Steps on how to position and manipulate the transducer will be provided in the video below. Once you have completed the ultrasound you will shut off the machine and clean off the gel medium from the transducer and treatment area. Please watch the video provided, to learn more about performing an ultrasound scan.

[Video for set up and performance of an ultrasound scan]

Transducer Movements

[Video of sliding, tilting, rocking, rotating, compressing in real time]

Axis of Visualization

[video of transverse and longitudinal axis of visualization]

Advantages

While it may provide less anatomical detail than techniques such as CT or MRI, it has several advantages which make it ideal in numerous situations

• Can view moving structures such as muscles and tendons to assess integrity and possible impingement throughout differing ranges of motion {MSK US Ian Beggs}
• Emits no ionizing radiation
• Can be used for elastography to assess tissue softening by measuring displacement before and after a compression force is applied{MSK US Ian Beggs}
• It is very safe to use and does not appear to cause any adverse effects, although information on this is not well documented
• Procedures are relatively inexpensive and quick to perform
• Ultrasound scanners can be taken to critically ill patients in intensive care units, avoiding the danger caused while moving the patient to the radiology department
• The real time moving image obtained can be used to guide drainage and biopsy procedures
• Doppler capabilities on modern scanners allow the blood flow in arteries and veins to be assessed {MSK US Ian Beggs}

Disadvantages/Limitations

The disadvantages and limitations of diagnostic ultrasound include:

• Equipment costs can range from $1,000 to $70,000 per device{uscultrasound}
• Ultrasound techniques require extensive anatomical knowledge and training {european society, sports ultrasound}
• Limited penetration due to more dense tissues blocking ultrasound waves {sports ultrasound}
• A lower frequency is required for optimal imaging of deep tissues leading to lower resolution images {european socitey}
• Incomplete assessment of joints and bone due to reflection of all sound waves back into the transducer head upon contact with bone {sports ultrasound}
• Anisotropy (part of the tissue that is there but not visualized) can occur when sound waves are not perpendicular to the targeted structure {european society}

Application of Ultrasound in Sports Injury

The ability to make correct ultrasonographic diagnosis in sports injuries is improving as advancing technology allows for high-resolution images in contemporary medical ultrasound. Ultrasonography demonstrates tissue structure with two-dimensional grayscale images. Blood flow in the tissue can be rapidly depicted with colour and power Doppler technique. Ultrasonography is the preferred imaging modality to study soft tissue lesions dynamically. With high-resolution images possible with ultrasonography, injuries of the muscle, tendon, ligament, bursa, bony structure, cartilage, and subcutaneous tissue can be accurately diagnosed (if the examiner is well trained). Recently, compact ultrasound machine machines are becoming increasingly available, leading to prompt ultrasonographic diagnosis of sports injuries on the field.